Propulsion of submarine boats.



C. DEL PROPOSTO.

PROPULSIONOP SUBMARINE BOATS.l

APPLICATION FILED 00T.5, 1907.

944,776'. Patented Dec. 28,1909.

` '2 SHEETS-SHEET 2.

, l '-xNv'ENTQR, vs. CSfDIODELPROPOSTQ r wwwm- CEsIDIo :DEL PRoPos'ro,or ROME, ITALY.

PROPILSION OF SUBMARINE BOATS.

Specification of Letters Patent.

Application filed October 5, 190'?. Sera1 No. 396,358.

To all whom it may conce-m:

Be it known that I, CiisiDIo DEL PROPOSTO, a subject of the King ofItaly, residing at Rome, Italy, have invented certain new and usefulImprovements in Propulsion of Submarine Boats; and I do hereby declarethe following to be a lfull, clear, and exact description of the same.

This invention has for its object to iniprove the means of production ofenergy for the propulsion of submergible or submarine 'boats of everykind, propelled under Water by compressed air (without batteries ofelectric accrunulators) and toincrease their radius lof action underwater while maintaining on board an energetic ventilation and acomfortable temperature. For the propulsion of submarine boats of thistype while under water,'the compressed air, has been until todayutilized in one of the two followingmanners: (l) The compressed airstored up in suitable reservoirs, is used to4 feed a compressedair-motor which drives the propeller shafts and then dischargesoutsidegthe boat. (9.) The compressed air is utilized merely to supportthe combustion in the cylinders of an internal combustion engine. In theformer case is utilized the i mechanical energy stored up in thecompressed air, in the latter case energy is produced by burning in thecylinders of the motor the oxygen conta-ined in the compressed air. Q

By adopting the system hereinafter set out the same compressed air canbe utilized successively in the two ways mentioned above,

Aand consequently, increases considerably the total work which can beproduced by means of a given quantity of air at a certain pressure. and,therefore, all other conditions being equal, it increases in the same`rate the radius of action of the boat under Water.

On the annexed drawing, 'Figure l shows schematically b y way of examplethe arrangement of the di'erent parts .l of, the motive apparatus, andFig. 2 a longitudinal section of a submarine boat according to thepresent invention.

In said drawing, -1-2-3-4- represent the four cylinders of an vexplosionengine by means of which the boat-while navi,-

gating' at the'surface is propelled and air is stored up through acompressor `-6f driven by the propel,ler shaft into [suitable reservoirsf-9.

Patented Dec. 28, i909..

and further to drive a subsidiary compressor 6.- which brings thecompressed air coming out from the 'cylinder -1'- and -2--, of the motorto the normall pressure of the reservoirs; thus ther compression will bemade in two successive steps and in two distinct engines. The aircompressed in the cylinders -1-, 2'- reaches the coinpressor 6 throughthe pipes 13" and 21- respectively. By such arrangement the power andalso the weight and encuinbraiice of the independent compressor canfbereduced considerably.

During the navigation under water the energy. for the propulsion of theboat will be supplied both by a compressed air motor and by theinternal' combustion motor, which, under water is kept ruiming just asin the open air. The airY escaping from the compressed air motor, isdischarged into the inside ofthe boat, circulates through saine andventilates it and then is aspired by the' internal combustion motor, anddischarged,

as combustion gases outside the boat. A

separate engine may'beemployed as a compressed air motor; but in orderto diminish the weight and encumbrance of the machinery on board,-itlisbetter to use, for this purpose,

either the same compressor 6 used for navigation (provided that itsconstruction allows itto be reversed) or one or more cylinders-forinstance the cylinder 1-,- or -1 and *2f of the internal combustionmotor,

(Wliich in -tliisfcase, should be polycylin- .storing the compressed airduring the surface case, therefore, during the navigation under l of thecompressed air motor; therefore it is water, the cylinders of theinternal combustion motor work partly in the usual way, and partly ascompressed air motors, so that the compressed air which is brought to asuitable pressure by means of a reducing valve l0 passing through thesubsidiary reservoir 8 reaches irst the cylinder 1 which acts as acompressed air motor or the cylinders 1 and` Q when the valve 23 isopen, is then discharged through the tube 12 in the inside of the boat.and is aspired by the other cylinders of the internal combustion motorthrough the tribe M by means of the pipes l5-7L, and discharged outsidethe boat at 16sthrough the pipes 13 and the exhaust box 11 From theforegoing it appears clearly that in the aforesaid system the same airis util- ',ized firstly to produce energy in the compressed air motor,by its expansive force,

and then, after having ventilated the boat, it is utilized incombination with an appropriate fuel to feed an internal combustionengine and thus is enabled to develop a. second time thermal energy forthe propulsion. T his system therefore reduces considerably the totalconsumption of air per H. P. transmitted to the propeller shafts. Withthe same object in view, viz. to reduce the consumption of air 4for eachH. P. developed it is advisable to use on board a compressed air motorwhich may be fed at the highest possible initial pressure, because, asis well known, the consumption of air per effective H. P. in compressedair motors diminishes when the admission pressure increases. It is alsoadvisable to select for this purpose an 'internal combustion engine inwhich the consumption of air per effect-ive H. P. be the smallestpossible; therefore it is also to be preferred a motor with a high finalpressure (Diesel type for instance) and the average pressure of which(average given by the diagram of the indicator) be the highest possible.Such a motor possesses the advantage not only of consumingT the smallestpossible quantity of air, but also of being less influenced by thecounter pressure in the discharge phase, which counter pressure, in asubmerged boat,- depends upon the depth of the immersion and tends todiminish the power which the motor can develop. lt is also known thatthe air consumption of a compressed air motor can be reduced by heatingpreviously the compressed air to a v convenient temperature; it isknownv as Well that said consumption can be still reduced considerablyif the compressed air is previously saturated with steam at thetemperature of admission.. Moreover the result of these two operationsisto increase the temperature of the air at the escape and thus vtoprevent the formation of ice in the cylinders convenient to adopt bothin the submarine boats of the aforesaid system.

In the compressed air engines working in the open air, the heatnecessary for the pre lilninary heating and for the saturation of thecompressed air is obtained by the combustion of an appropriate fuel butthis must be avoided as much as possible on board of submarine boatsbecause the combustion of the fuel results finally in an additionalconsumption of air. lt is possible to reduce or even to avoidcompletely' any air consumption for this purpose: (l) by utilizing asmuch as possible in performing said operations the heat still containedin the escape of the internal combustion motor;

hy increasing if necessary, the heat contained in said gases, .byburning in their midst a convenient fuel; and this is always possiblebecause the gases escaping from the internal combustion engine containunavoidabl)v a considerable percentage of lmlmrncd free o.\' gen, which,under suitable conditions can support. the combustion of a certainquantity of fuel. Practically the heating andthe satu ation of thecompressed air will be performed by circulating the compressed airwithin a closed vessel ll in the. ordinary apparatus provided therefor,with the cxception however that said apparatus have to be heated in themanner mentioned above. that is in the exhaustbox by means ofthe exhaustgases ,escaping through the pipes 13 from the cylinders 2 3- 1 a Byemploying the above mentioned process for the utilization of thecompressed air, coming out from the reservoir Q and reaching thecylinders 1 and Q through 10 8 11 l5 13 2l logether with the heating andsaturation by heat of the exhaust gases, in the exhaust box ll it ispossible to reduce the consumption of air per efi'egtive H. P. developedon the propeller shaft downto limits heretofore unknown. And in fact,all other conditions being equal, the weightl of the machinery on boardbecomes much less than the weight of the machinery for submarine boatspropelled under waterby a battery of electrical accumulatore, or even bycompressed air utilized in the manner now generally in use.

The total efficiency of the compressed air utilized as a motivefpower isreduced: by the losses of energy in the compressor, (2) by the losses ofenergy in the compressed air motor, and also by the fact that thepressure in the reservoirs is.. generally higher than the allowableinitial pressure in the compressed air motor, so that the use of areducing valve 10 is necessary, while the preliminary heating andsaturation -of the com ressed'air by means of the exhaust gases o theexplosion engine is an excellent method of utilization of the heatstored sion, there may Aiugthe indications of the barometer,

in said gases and tends to enhance the total efficiency mentioned above.Byconveniently regulating the work of the Various parts olf the wholeplant it is possible to increasethe total efficiency of the compressedair used in this way almost up to unity.

In the foregoing the fuel consumption has never been considered,because, during the navigation under water it is very small incomparison with the consumption-of air and because the diiiiculty ofstoring the necessary fuel is beyond comparison less than that of, Ystormgthe compressed air.

The barometrical pressure 1n a submarine boat of the type consideredmustremain almost constant, during the navigation under Water and notmuch different from the ordinary atmospheric pressure and independentfrom the depth of immersion of theboat. This condition is'evidentlyrequired by the welfare of the crew and also for the satisfactoryWorking of the explosion engine, because the air pressure in themachinery room is an important factor in the working of the engines andit contributes in determining the pressure developed in the cylinders,and iniuences the combustion as Well as the extreme temperatures of thelcycle; therefore considerable variations of pressure in the interior ofthe boat are not ad# missible.4 The barometric pressure inside the boatunder Water Will remaln statlonary provided-that the quantity of exhaustair escaping from all the compressed air engines (on board, besides thecompressed air motor which produces the energy for the propulbe othercompressed air engines for vvarious services, the exhaust of which isdischarged also inside the boats) be equal to the quantity of airaspirated by the explosion engine, with the combustion gases, boat. Theindications of a barometer permit therefore to ascertain Whether theaforesaid correspondence is maintained and show how to eventuallyregulate the pressure.

vShould the vpressure beginto differ from the normal one, as thequantity of air absorbed by the internal combustion motor cannot beeasily modified, then, in or( er to 'reestablish the balance and tomaintain the pressure statiol1ary,:'tlie best way is to modify,automatically or by hand, follovt 1e quantity of airjadmitted into thecompressed air motor dl'- which supplies partly the energy for thepropulsion.

The 'temperature in a submarine boat of `the typeI` described during thenavigation under water tends to increase because of the heat Vradiatingfrom the internal combustionmotor`and at the same time it tends todimmish because the exhaust air of the compressed air engines althoughhaving-been- "previously heated 'is cold; there is therefore a certaincompensation.

and expelled, together outside the Within certain limits and by theapplication of the means "generally known it is possible to diminishtheradiating heat of the motor and also the temperature of the exhaust airof the coinpressed air engines; but the best protection against theelevation of the temperature is afforded by the ventilation, which isvery energetic in the boats of the type described because the Whole air,which is directly or indirectly used as mot-ive power is utilized c init.

A serious inconvenience in the submarine boats driven under Water by aninterna-l combustion motor is the bad smell produced vby the emanationsof the fuel (mineral oil,

benzin etc.) reaching in the interior of the boat through.insufficiently tight joints of the pipes or due to leakages in variousparts of the engine; to prevent the spreading of said emanations intothe part of the boat occupied by the crew the following arrangement isadopted. The exhaust, air of all thecompressed air engines -lisdischarged inside the boat at the end -.12- thereof usuallyioccupied bythe crew, while the aspiration of the internal combustion motor. -1-2-3-takes place at the op posite end -14-' of the boat, so that theWholeinside of the boat is constantly swept by a draft ofair. Inanylpoint Whatever of the boat the speed of said air `current is ininverse ratio of the free crosssection afforded to its passage;therefore by means of suitable partitions -24- it will be possible toincrease considerably the speed of the air current Where it will benecessary and arrange said partitions for instance in such 1nanner,-thatin proximity.

of the engines'the current be strong enough to carry 0H to the other endof the boat any emanation Where the foul air is absorbed by theaspiration of the internal combustion mot-or.

To keep the boat at a constant v,depth during the navigation underwater, the Weight of the boat must remain unaltered; therefore inthe-boat the Weight of the exhaust gases of the internal combustion.motor discharged Aoutside must beI substituted by an equivalent Weightof water; and as the weight of the exhaust gases (at least for certaintypes of internal combustion ruotors) is almost in proportion of thenumber of turns of the motor, because the quantity of air absorbed ateach pistons stroke is almost unvaried; and the Weight of the Afuelburned can be neglected in comparison with the-Weight of air necessaryfor the` venient capacity and actua-te by the motor for instanceconveniently .connecting same llO with the propeller shaft, which pumpintroduces water from' the exterior through the pipe 26 when the motoris running. The weight of the exhaust gases at each turn of the shaftbeing a known quantity by a given motor, it'fol-lows that it will be aneasy task to determine the size and the speed of the water pump whichwill keep the load of the boat unvaried.

In submarine boatsfor military services, it.- is desirable that thedischarge of the exhaust gases of the internal combustion motor besuppressed when the boat gets very near the enemy because the bubblingcaused -at the surface of the water by the said exhaust gases may helpin detecting the presence of the boat. To avoid such inconven iece, thepropulsion' in said case'is made as follows'. When the boat is very nearthe enemy, her engines are run exclusively as compressed air motors, theexhaust air of which is discharged, as before, into the inside of theboat. Under these conditions the barometrical pressure in the boat willincrease slowly up until the maximum which the men of the crew and theresistance of the hull are able to support. It is easy to figure out,that before such limitis reached, a. sufiicient length of time willelapse to allow the boat to get away to a distance, where the bubblingcan be no more noticed. Then the 'engine is again run, exclusively as aninternal combustion motor in the same manner as when the boat is at thesurface of the Water until the barometrical pressure in the inside ofthe boat lowers -anew to the normal atmospheric pressure; at this pointthe normal propulsion by the compressed air motor and the explosionengine will be resumed. It should be remarked' however that, astheinternal combustion motor could not work, properly where the externalair pressure is sensibly superior to the atmospheric pressure, on theair inlet ipe must be provided an au tomatic reducing valve, -18- whichbrings the air pressure down to-the valueconvenient for the normalWorking of the motor. In passing it should be remarked that by such aprocess the air is utilized twice as in the former case, but the 'twosteps of the cycle are successive instead ofbeing simul-.

taneous. Therefore by adopting the system above described, the dischargeof the exhaust gases outside of the boat can be su pressed during alimited-tim'e,and of this possibility the boat will take advantagevwhenever the bubbling of the water at the surface becomes dangerous.

In sulnnarne boats for military service,

'the reduction to a minimum `of the time required by thelu'rat to passfrom surface navigation to the submerged position is a very importantfeature. VThe immersion is obtained by fillingq with water-ballasttanks,

-erate as an air motor to ,assist it is important therefore, to performthis operation as quickly as possible and this can be done by producingavacuum in the ballast tanks, 'for this purpose an air pump may be used,but the best means is to so arrange some of the cylinders of theinternal combustion motor as to enable them to act as air pumps, forinstance the same cylinder '-1 which according to the variouscircumstances acts as an internal combustion motor, as a compressor, asa compressed air motor, and as an air pump.

Claims:

1. In a submarine boat, an engine having a plurality of cylinders, anair compressor driven by said engine and a storage reservoir wherein thecompressed air is stored: one of the cylinders of the engine adapted toact as an air' compressor, to effect a first step in the compression ofthe air while the i boat navicates at the surface air connections fromsaid compressor cylinder to the first-A mentioned compressor to completethe air compression, connections from said reservoir to said compressor,-said air compressor operated by the remaining cylinders ofthe engineWorking in the usual way.

2. In a submarine boat, the combination of a polycylindric explosionmotor for propelling the boat, an air compressor for serving at will asan air motor to assist in propelling, a reservoir for compressed air,con- .nections between said compressor and reservoir, and connectionsbetween the latter and a. plurality of cylinders of the motor, wherebythe latter is adapted at Will to oppulsion.`

3. In asubmarlne boat, the combination of a polycylindric lexplosionmotor for pro'-l pelling the boat, an air compressor driven by saidmotor, a compressed air reservoir connected with said compressor, meanswhereby several cylinders-of the explosion motor a-re enabled to act asa compressed air motor atwll. to assist in the propulsion, and areducing valve inserted between the aforesaid air reservoir andcylinders.

4. In a submarine boat, an engine for propelling the boat, an aircompressor which,

at will, acts also as a compressed air reser-4 voir, means for admittingcompressed air from the reservoir into the air compressor while actingas a compressed air motor, eX- haust connections from said compressedair 4motor to the interior of theboat, and feed connections from theinterior of the boat to the engine, to supply air to the latter.

5. In a submarine boat, the combination of a polycylindric motor forpropelling the vin the proboat, an air compressor driven thereby, a f

compressed air reservoir connected therewith, means wherebythe a1rcompressor and 'a plurality of cylinders of the 'explosive motor areenabled to act, at will, as a compressed sion of the boat,connections asa compressed pressed air motor-io cylindersl oi the engine acting alsoas com' air motors, means for discharging the exhaust air of the latter'in the interior of the boat, and means Jfeeding into theremaining*cylinders o't' the explosion motor, air taken from theinterior of the boat.

(3. In a submarine boat,the combination oli a combustion engine forpropelling the same, a compressed air motor to assist in propelling theboat and having an exhaust valve, a compressed air reservoir andconnections for feeding compressed air to cylinders of said motor, aclosed vessel for receiving and circulating compressed air coming fromthe reservoir before reaching the cylinders, aforesaidY of thecompressed air motor, and connections' between the exhaust valve of theengine and said closed vessel for allowing the exhaust gases of theengine to heat the air which is circulated in the closed vessel;

7. In a submarine boat, the combination of a polycyli'ndric engine forpropelling `the boat, an air compressor, driven by saidV engine, acompressed air reservoir connected therewith and wherein the compressedair is stored, a plurality of thecylinders of the thermic engine adaptedto' act, at will, as air compressors to effect a irst step in thecompression of the air, connection from the air reservoir to the aircompressor whereby the latter is enabled to act, at will, as compressedair motor to assist 4in propulsionfof the boat,l suitable connectionsbetween those cylinders of the engine' where the first step of thecompression of the air is effected and the air compressor where thecompression o air is completed, and a closed vessel for receiving theexhaust gases of the engine in order to heatthe compressed aircomingfrom the reservoir before reaching the air compressor when act-ing fas acompressed air motor;

8. In a submarine boat, the combination of a polycylindric engine forpropelling the l l l l boat, an l air.

storage reservoir for compressed air, a numcompressor driven thereby, a*

adaptedlto act, at will, as air compressors ,e

to effect-a first stepof the compression, and a compressedair motor toassist inthe propulsion ofthe boat, a reducing valve inserted between'the air rservoir andthe mentioned cylinders of the engine, and a heatingapparatus for receiving the exhaust gases of the cylinders acting asexplosion engine, and a conduit connecting the storage reservoir,withthe cylinders acting as com pressed-air-motors and passing through theheating apparatus, .whereby gases are utilizedfor heating the air whichcirculates in said conduit.

the exhaust y 9. In a submarine boat, a motor fr driving said boat,means foi-.causing said motor to also drive a compressor, when the boatis nea'r the 'surface of the water, a suitable reservoirfor storingsaidcompressed air, a compressed air motor to assist in propelling the boatunder water, connection from the res ervoir to .said compressed airmotor for supplying compressed air to the lat-ter, an exhaustvalveprovided on said compressed air motor and through which theinterior of the boat, and inletvalves on the engine and which, when theboat is under water admit the air from the interior of theboat forgupporting combustion in the cylinders of the engine.

10. In a submarine boat, motor and a combustion engine having aplurality of cylinders, a vconduit for discharging the exhaust air ofthe cylinders which act as compressed air motors` at one end of theboat, another' conduit from the inlet valve of the engine to the otherend of the boat, for supplying air to the engine, and partitionsprovided iu convcnimu; places inthe interior of the boat and reducing,at said places, the clear section, to increase the speed of the aircurrent which goes from one end of the boat to the other.

In testimony whereof,-l. have signed my name' `to this specification inthe presence of two subscribing witnesses.

J. GRoN, ILA. JOHNSON.

a compressed air air is discharged into

